Wind power generation is typically provided by a wind “farm” having a large number (often 100 or more) of wind turbine generators. Individual wind turbine generators can provide important benefits to power system operation. These benefits are related to mitigation of voltage flicker caused by wind gusts and mitigation of voltage deviations caused by external events.
In a wind farm setting, each wind turbine generator can experience a unique wind force. Therefore, each wind turbine generator can include a local controller to control the response to wind gusts and other external events. Prior art wind farm control has been based on one of two architectures: local control with constant power factor and farm level control in fast voltage control, or local control in constant voltage control with no farm level control.
Both of these prior art control architectures suffer from disadvantages. Local control with constant power factor and farm level control in fast voltage control requires fast communications with aggressive action from the farm level to the local level. If the farm level control is inactive, the local control can aggravate voltage flicker. With constant voltage control on each generator, steady-state operation varies significantly with small deviations in loading on the transmission grid. This causes the wind turbine generators to encounter limits in steady-state operation that prevent a response to disturbances, resulting in a loss of voltage regulation. Because reactive current is higher than necessary during this mode of operation, overall efficiency of the wind turbine generator decreases.
Accordingly, improved voltage control systems and techniques for use with wind turbine generators would be welcomed in the art.